Toner Core-Shell Additives for Heat Resistance and Charge Stability
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Solution Overview
Problem
Existing toners face challenges in maintaining charge characteristics and heat resistance, especially in high temperature and high humidity environments, due to issues with hydrophobicity and affinity of external additives with toner mother particles.
Innovation Solution
The toner incorporates external additive particles with a core-shell structure, where the core particles have a high hydrophobicity degree and the shell particles have a low hydrophobicity degree, ensuring sufficient affinity and preventing detachment from toner mother particles, while maintaining appropriate hydrophobicity to improve heat resistance and charge stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If external additives with high hydrophobicity are used to improve heat resistance, then heat resistance is improved, but charge characteristics deteriorate due to charge decay
Solution Approach 1:
The external additive is segmented into a core particle and multiple shell particles. The core particle has high hydrophobicity (hydrophobicity degree of 70% or more) to provide heat resistance, while the shell particles have low hydrophobicity (hydrophobicity degree of 30% or less) to maintain charge characteristics. This segmentation allows both contradictory requirements to be satisfied simultaneously by distributing different functional properties to different structural components.
2Stability of the object's composition
If external additives with high affinity to toner mother particles are used to prevent detachment, then affinity is improved, but hydrophobicity decreases leading to poor heat resistance
Solution Approach 1:
Different regions of the external additive structure are assigned different hydrophobicity levels to fulfill different functions. The core particle region maintains high hydrophobicity for heat resistance, while the shell particle region has low hydrophobicity to ensure high affinity with the toner mother particle surface. This local differentiation of properties resolves the contradiction between overall hydrophobicity and local affinity requirements.
3Stability of the object's composition
If shell particles with small diameter are used to increase surface coverage, then affinity is improved, but manufacturing precision becomes difficult to control
Solution Approach 1:
The invention specifies precise parameter ranges for shell particle diameter (0.01 μm to 0.5 μm) and core particle diameter (1 μm to 10 μm), along with their ratio (0.01 to 0.5). By controlling these parameters within defined ranges rather than optimizing for a single value, the invention achieves both good surface coverage for affinity and manufacturability. The parameter change approach allows flexibility in production while maintaining performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enhances the toner's heat resistance and charge characteristics, preventing aggregation and charge decay, even in harsh environmental conditions, by ensuring strong affinity between the external additives and toner mother particles.
Implementation Method 1
a plurality of shell particles adhering to a surface of the core particle
Implementation Method 2
an external additive adhering to a surface of the toner mother particle
Data Source
AI summary
Toner particles each include a toner mother particle and a plurality of C/S external additive particles. The toner mother particle contains a polyester resin. The C/S external additive particles each adhere to a surface of the toner mother particle and include a core particle and a plurality of shell particles. The shell particles each adhere to a surface of the core particle. The shell particles have a number average primary particle diameter of no greater than 0.40 times a number average primary particle diameter of the core particles. The core particles and the shell particles each contain a resin. The core particles have a hydrophobicity degree of at least 30%. The shell particles have a hydrophobicity degree of no greater than 5%. The C/S external additive particles have a hydrophobicity degree of at least 15% and no greater than 25%.